[65nss4spdGTO]

The head wars continues in the race section, but what does it take to have a better or best cylinder head for boosted applications.

The bar is set by the Butlers and Quillen, don't leave out the heads Mark and and Mike did for the Boss Bird.

Lets hear your comments.

Calvin Hill
Hill Performance
708-250-7420

[BrandX]

Depends... blowers need lots of cylinder head. Turbos dont seem to need it as much. With a turbo deal its really more about staying sealed up and reliable. The power will be there.

I have an 03 chevy pickup with a 6 liter. Its got stone stock ports and combustion chambers. Stock rocker arms even. But makes 1000+ hp to the tires with a single small frame 88 t4. Sure I could put an expensive high flowing port on there, and it might make the same power at less boost....but if everything is sealed and reliable who cares what the boost guage reads???

[Travis Q]

Originally Posted by 65nss4spdGTO

The head wars continues in the race section, but what does it take to have a better or best cylinder head for boosted applications.

The bar is set by the Butlers and Quillen, don't leave out the heads Mark and and Mike did for the Boss Bird.

Lets hear your comments.

Calvin Hill
Hill Performance
708-250-7420

Depends ENTIRELY on the combination. Blowers and turbos like something totally different. Roots blowers and screw blowers are also a little different. Centrifugals are their own bastard deal as well.

Like BrandX said, one of the biggest things is the durability of the deal, including the material. This is where a lot of aftermarket heads fall really, really short. It's tough to keep a sponge clamped up, and this is where a billet head like the one that Eric and Mike have done really shines. I've seen some cast heads that just wouldn't stay put, and it was due entirely to the quality of the casting. I swear, some aftermarket heads look like swiss cheese with all the porosity. And i'm not talking about Pontiac heads specifically. Impossible to keep a head gasket on something like that.

So I guess if you want to know what the ingredients are in the ideal cylinder head for boosted applications, I'd say a billet is definitely one of them.

TQ

[v869tr6]

A large chamber so a off the shelf flat top piston could be used. Melting pistons sucks, waiting 6 weeks for custom pistons sucks worse.

[taff2]

How about a factory cast iron head with a little bit of porting? Definately better clamping than an ali head,easy to find with big chambers,cheap!
An aftermarket cast steel head with good ports would be nice for budget minded turbo guys in my opinion.

[70 bird]

I use a set of 6x's ported with the direction of Jim Hands book, seem to work good. IF I was in the market for a better flowing set I would look at a set of cv1's with the largest cc runner they make, jmo.

[BruceWilkie]

http://users.erols.com/srweiss/tablehdc.htm#Pontiac APD 6x vs all the other ported heads if you want to compare.

Hot Rods F-Bomb twin turbo 406 sbc by Nelson... Made 1502 hp at 5600 rpm 28.5 psi
At 6000 rpm 18.3 psi it made 1165.
On 91 octane pump gas at 5800 1025hp 14.6 PSI
Compression is 8.96
Cam Solid XE 276 street roller (4873) lobes 236/236 @.050 115LSA(about .600 net lift)
Air/Air intercooler. Heads were Brodix 11x

My build...
407 ci, 6x-8 APD Iron heads at 8.25-8.5 compression (should be about equal to aluminum at 9:1.)
Air/Water intercooler and a slightly different cam, maybe 500 more rpm, Bigger throttle body, Possibly a pair of S475's(t6 83mm 1:10 ar turbine) but 72's will work fine. I think I can beat Nelsons numbers by quite a bit.

I'll likely cam and rocker to .625-.650 net lift and have different cam specs in mind... Dont think I need to go past 7k rpm to beat Nelsons package.

Havent decided on exhaust side of head yet... My test head might get the snoots cut.

Calvin... Bill finished where I left off. I was at 235 cfm with bad nicked untouched 100k mile factory valve job, my less experienced porting... Bill fixed a few things did a good valve job and it jumped to 265 and was peaking early like most d-ports(it was fat early though). Then starting with same theme as mine he blew out a port to see its limits then did another one at safe limits but better overall shape than mine. I do need to run offset intake rockers(.150" 4 left 4 right) but dont need shafts.

APD 6x flow numbers vs Brodix 11x. Brodix 11x head has 2.08 valve 227cc volume

Brodix 2.08 APD 2.10
vvvvv vvv
.100 xxx 74.6
.200 133 148.3
.300 191 217.1
.400 235 250.6
.500 272 274.4
.600 283 284.6
.650 284 xxxx
.700 285 289.8
.800 xxx 292.4

Dont just look at the peak...those middle numbers are important.

Considering the deep chamber and less than nice short turn on 4x and 6x heads those are very strong numbers. The bench is exceptionally quiet thru the lift curve.
Late 60's small chamber heads should be able to provide more flow. Especially round ports.

Dont really need it at this engine size. Marty P was over 1600hp in 93 with a 406 and iron heads in the 270 range. No intercooler but alky at 38 psi.

Anyway I like that iron clamps better... CV1 re-tool or Bills cv235 port would be my second choice.(1st if it was iron) CV1 355 alloy vs all the other Pontiac choices using 356 the CV1 will hold up under heat better. Jims castings certainly arent porous.(BTW Dart heads use same 355 alloy as cv1)

These heads could support 1700 -1800 hp at 30psi with the right turbo's, intercooler and support pieces. I'm guesstimating my 407 should exceed 500 hp NA at 8.4 compression under 7000 rpm. (my base goal is 530+ Guess we'll have to see on that though. It is doable.)

[thadeal4real]

I got a lot to say about this but brandx hit on it it's all about the combo and how far you want to push it

[RUDOLFSSON]

5 years and no head gasket fails yet.... 150++mph 3650lbs street car, max 25psi boost. Iron heads make the deal reliable for sure!

[Elarson]

I would agree that if you are talking stock size, water-jacketed heads, the nod should go to cast iron. It's roughly 3x the stiffness, has a higher melting point and less thermal expansion (compared to aluminum).

Our billet head is taller than stock (adds stiffness), no water jackets (adds stiffness) and has RA5 valve layout to separate the heat of the center exhaust ports.

FWIW,
Eric

[Lee]

Originally Posted by BrandX

Depends... blowers need lots of cylinder head. Turbos dont seem to need it as much. With a turbo deal its really more about staying sealed up and reliable. The power will be there.

I have an 03 chevy pickup with a 6 liter. Its got stone stock ports and combustion chambers. Stock rocker arms even. But makes 1000+ hp to the tires with a single small frame 88 t4. Sure I could put an expensive high flowing port on there, and it might make the same power at less boost....but if everything is sealed and reliable who cares what the boost guage reads???

Similar findings with turbos. My friend's truck has a 6.0 block with a 4.0" stroker crank, a homebuilt turbo kit, and unported L92 heads. I designed the cam, and my friend tuned the motor (HPTuners) himself. At 14psi, with a LOOSE converter, on a DynoJet, it has put 1168hp to the wheels.

I'm certain it will make more power with better heads, but I doubt the improvement would be nearly what you'd expect in a N/A or supercharged motor.

[BruceWilkie]

Lee... if the turbo has the flow capacity from compressor and turbine(pressure differential (delta) at zero or positive) ... a 500 hp na motor should be capable of 1000 hp at @15 psi....1500 @30 psi. too small a turbine can restrict this. (far easier to get near zero differential with twins than a single)

So...if you have heads that add another 50 NA hp... you should see double the gain at double atmospheric pressure... in other words 1100 Hp boosted to 15lbs and 1650 at 30 psi if new heads put you at 550 NA.

Many may not see the gain as the potential can be eaten up by backpressure... You need a turbine big enough to drive the compressor for the air and pressure demand, a smallish a/r for the turbine size to aid spool and a big gate for no exhaust restriction.

btw... A/r numbers are specific to the turbine wheel and housing being used.

Borg Warners matchbot, though applicable only to BW turbos, is quite good.
here's one to play with...(ignore some of my inputs..I was just playin) http://www.turbodriven.com/performan...6_wrsin=92044&

create your own...there are tutorials at the bottom to help you. Also if you mouse over the question marks next to the inputs it will guide you.

[Lee]

Bruce, thanks for the link/info! We are having fun with the turbos, and I know there is a LOT left to learn. We got a twin-turbo system fired up a few days ago, but haven't had a chance to dyno it yet - it seems very responsive though. We've got a couple of milder single-turbos running around now, and a few others in the works.

These turbos (and the LS motors) have made me rethink many of my old beliefs!

[65nss4spdGTO]

Originally Posted by BrandX

Depends... blowers need lots of cylinder head. Turbos dont seem to need it as much. With a turbo deal its really more about staying sealed up and reliable. The power will be there.

I have an 03 chevy pickup with a 6 liter. Its got stone stock ports and combustion chambers. Stock rocker arms even. But makes 1000+ hp to the tires with a single small frame 88 t4. Sure I could put an expensive high flowing port on there, and it might make the same power at less boost....but if everything is sealed and reliable who cares what the boost guage reads???

Ok.

Quality and stability of the material would be job 1.

What about CSA? The factory iron heads are very small, lets say the target is 1250 HP to 1500 HP on a 455ci Pontiac. Big ports, high air speed, velocity, where do these things come into play?

Calvin Hill
Hill Performance
708-250-7420

[Travis Q]

And give me room for at least 5/8" pushrods and 1.750" springs, please.

And an intake port that, when I look down through the port opening, I can see almost all of the valve seat. For reference, see a 481X AJ motor. Or a Brad 8. Oh, and don't bother sending a flow sheet. I don't care. LOL

And a combustion chamber that's pretty open. None of the shallow valve angle/ultra small chamber volume stuff, please. 75-80cc should do the trick.

And six 9/16 studs per hole, 18 total. Well, the ten outside studs can be 1/2". I'll live with that.

Then I will be happy.

[Travis Q]

1500 on a 455? you already have the ideal head for that. It's an out of the box Edelbrock with good valves and springs. Seriously.

I just finished freshening up a little 347 inch (3.25 stroke 4.125 bore) SBF I built for a customer. It had out of the box Victor Juniors, no port work, no port match, just good stainless valves and PAC springs that are 330 on the seat. They flowed 267 on a SuperFlow bench (the Butlers').

That car made over 1400 at the tire and went an 8.09 at 178 in a 3480 lb car with stock suspension and 275 radials.

Really, we already have a number of heads for this power level. It's like falling off a log backwards, it's so easy.

EDIT: AFter reading again, one thing to consider is engine speed. If we're below 7500 with that 455, then an out of the box head, or one with a tootsie roll cleanup will do it. If you want to spin it higher, you may need to increase CSA a little bit.

[Marty Palbykin]

Originally Posted by Travis Q

And give me room for at least 5/8" pushrods and 1.750" springs, please.

And an intake port that, when I look down through the port opening, I can see almost all of the valve seat. For reference, see a 481X AJ motor. Or a Brad 8. Oh, and don't bother sending a flow sheet. I don't care. LOL

And a combustion chamber that's pretty open. None of the shallow valve angle/ultra small chamber volume stuff, please. 75-80cc should do the trick.

And six 9/16 studs per hole, 18 total. Well, the ten outside studs can be 1/2". I'll live with that.

Then I will be happy.

Travis, I respect you opinion, here is mine on the Pontiac a solid head hemi of course, 1/2 tool steel push rods and a exhaust port at 80% plus. x bolt main on a aluminum billet block. I don't really care how big it is with turbo's and alc in 1970's these engines made 10 hp. per cubic in . My question is how hard would it be to make a billet hemi head for a Pontiac? I honest to god would fund a project like this, but we don't have the parts.
Just my opinon just like ass*** we all have one. To summarize a bae 8 port on a Pontiac.
Most don't know a standard hemi is 4.187 bore. best regards Marty P.

[BruceWilkie]

Originally Posted by Travis Q

1500 on a 455? you already have the ideal head for that. It's an out of the box Edelbrock with good valves and springs. Seriously.

I just finished freshening up a little 347 inch (3.25 stroke 4.125 bore) SBF I built for a customer. It had out of the box Victor Juniors, no port work, no port match, just good stainless valves and PAC springs that are 330 on the seat. They flowed 267 on a SuperFlow bench (the Butlers').

That car made over 1400 at the tire and went an 8.09 at 178 in a 3480 lb car with stock suspension and 275 radials.

Really, we already have a number of heads for this power level. It's like falling off a log backwards, it's so easy.

EDIT: AFter reading again, one thing to consider is engine speed. If we're below 7500 with that 455, then an out of the box head, or one with a tootsie roll cleanup will do it. If you want to spin it higher, you may need to increase CSA a little bit.

Calvin, I have to agree with Travis that the out of box E-head with good valves and springs is a good target for 1200- 1500HP for 400-455. Personally I think a good ported IRON head that flows similar is a physically stronger choice.

Besides my 6x Bill has done a bit on some smogger round ports lately that show some great potential. He got some good results with far more constraints than I gave him.

fwiw I wouldnt use a 3.25 main stock block for that power level and I'd be cautious on stroke. Turbo more than makes up for cubes. My little 164 ci corvair beat up big block musclecars in early 70's with 60's tech with just a turbo upgrade. Maybe 300 hp drawing through a holley 2 barrel and exiting through a muffler.(2.5"glasspack). Stock internals I never took it much beyond 5500. Plus air cooled tortured intake and exhaust arrangement. Cubes arent critical! Especially with todays technology.

[Travis Q]

Originally Posted by Marty Palbykin

Travis, I respect you opinion, here is mine on the Pontiac a solid head hemi of course, 1/2 tool steel push rods and a exhaust port at 80% plus. x bolt main on a aluminum billet block. I don't really care how big it is with turbo's and alc in 1970's these engines made 10 hp. per cubic in . My question is how hard would it be to make a billet hemi head for a Pontiac? I honest to god would fund a project like this, but we don't have the parts.
Just my opinon just like ass*** we all have one. To summarize a bae 8 port on a Pontiac.
Most don't know a standard hemi is 4.187 bore. best regards Marty P.

I'm with you Marty, the Hemi type head would work great too for a turbocharged application. I've got some ideas on this that I'll keep under my hat for now (until we talk on the phone ) but it would be a cool deal.

Getting these heads made isn't all that difficult, it's the design work in terms of layout of all the ports and valvetrain that would tke a little time. I can name three shops right now that would do the CNC work.

BAE on a Pontiac = BIG power......and BIG durability, too!!

[65nss4spdGTO]

So what I'm hearing, it doesn't matter what cylinder head is used?

For discussion purposes, I picked 455ci, not planning to use a stock block for the level of power, but more about the ci.

The recipe is: Aftermarket Pontiac block with 3" mains. 4.000" stroke, 4.250" bore, just under 455 ci. Now here are the three head choices, lets assume they all have high quality valves and hardware, the all of the same 10 head bolts, 1 cast iron, 2 casted aluminum. This is a wild street car with a goal of 1250 HP to 1500 HP.

Head 1
Cast Iron, 2.150" x 1.750" valve package, 2.600" CSA at entry, flows 275/220 CFM @.600" lift.

Head 2
HQ casted aluminum, 2.200" x 1.750" valve package, 3.000" CSA at entry, flows 350/265 CFM @.700 lift.

Head 3
HQ casted aluminum, 2.250 x 1.700" valve package, 3.600" CSA at entry, flows 430/285 CFM @.800 lift.

All heads have the same EIIEEIIE layout, uses shaft rockers, they all must use a version of the Edelbrock Victor manifold ported to match each cylinder head with EFI.

What are the pros and cons with each cylinder head, lets hear your thoughts.

Thanks.

Calvin Hill
Hill Performance
708-250-7420